Metallothionein rescues doxorubicin cardiomyopathy via mitigation of cuproptosis.

Doxorubicin (DOX), a chemotherapeutic agent utilized in the management of cancer, provokes cardiotoxicity although effective remedy is lacking. Given that DOX provokes oxidative stress and cell death in cardiomyocytes, this study evaluated the possible involvement of cuproptosis, a newly identified form of cell death, in DOX-instigated cardiac remodeling and contractile dysfunction, alongside the impact of the heavy metal scavenger metallothionein (MT) on DOX cardiomyopathy. Cardiac-specific MT transgenic and wild-type (WT) mice were treated with DOX (5 mg/kg/wk., i.p., for 4 wks) prior to assessment of cardiac morphology and function. DOX evoked cardiac remodeling (interstitial fibrosis), compromised echocardiographic (thinner septum, elevated LVESD, reduced ejection fraction and fractional shortening), cardiomyocyte mechanical and intracellular Ca properties alongside mitochondrial injury (ultrastructure, respiration and mitochondrial membrane potential), oxidative stress (higher O and ROS, lower GSH level), apoptosis and cuproptosis (upregulated CTR1 and DLAT, downregulated copper exporter ATP7B, FDX1, the FeS cluster proteins ACO2 and NDUFS8). Bioinformatics analysis confirmed enrichment of copper-related genes among DEGs in DOX-challenged hearts. DOX-induced anomalies (except the copper importer CTR1) were reversed by MT overexpression. Co-immunoprecipitation and interaction interface revealed a prominent interaction between MT and ATP7B. Further study indicated that copper chelator tetrathiomolybdate mitigated DOX-induced cardiac remodeling and cardiomyocyte abnormalities whereas copper ionophore elesclomol nullified MT-mediated benefit against DOX. These findings favor a vital role for cuproptosis in DOX cardiomyopathy while the antioxidant MT rescues DOX cardiomyopathy possibly through alleviating cuproptosis.